1. Field of the Invention
The present invention relates to an exhaust gas purification system for a vehicle. More particularly, the present invention relates to an exhaust gas purification system for a vehicle, and a regeneration control method thereof, that is adapted to perform unifying control of regeneration and desulfurization, which are regeneration of a particulate filter that is adapted to trap particulate matter (PM) such as soot included in exhaust gas, and desulfurization of a lean NOx trap (LNT) that is adapted to absorb or adsorb nitrogen oxides (NOx).
2. Description of Related Art
A lean burn engine has been widely used for improving fuel consumption of a vehicle.
According to reinforcement of exhaust gas regulations, in a general vehicle having the lean burn engine, a lean NOx trap (LNT) is mounted at a rear end of an exhaust manifold and a particulate filter (PF) is mounted at a rear end of the LNT so as to reduce noxious exhaust gases.
The LNT absorbs or adsorbs nitrogen oxides (NOx) generated by the lean burn of an engine. In addition, the LNT reduces NOx to nitrogen gas (N2), and then exhausts the N2.
The NOx storage of the LNT is reduced or deteriorated by sulfur poisoning. Sulfur components are included in a fuel and engine oil. Therefore, purification performance of NOx should be recovered through desulfurization.
The particulate filter physically traps particulate matter (PM) such as soot included in exhaust gas, and then filters the trapped PM. In addition, the trapped and filtered PM are periodically regenerated according to the amount of trapped PM filtered by the PF, travel distance or time of a vehicle, or differential pressure between front and rear ends of the particular filter.
The regeneration of the particular filter is performed through combusting the trapped PM as the temperature of exhaust gas is increased to a high temperature of about 600° C. to 700° C.
Both the regeneration of the particular filter and the desulfurization of the LNT are performed at the high temperature of about 600° C. to 700° C.
Generally, the regeneration of the particular filter is performed when the temperature of the front end of the particular filter is increased to a high temperature, and then the desulfurization of the LNT is performed by using the high temperature.
The incomplete regeneration of the particular filter is minimized, when the desulfurization of the LNT is performed after complete regeneration of the particular filter. However, the time and amount of fuel consumed during the regeneration and the desulfurization are excessively increased, and thus fuel consumption may be deteriorated and generation of noxious exhaust gases may also rise.
The information disclosed in this Background of the Invention section is only for enhancement of understanding of the general background of the invention and should not be taken as an acknowledgement or any form of suggestion that this information forms the prior art already known to a person skilled in the art.